Genomic Surveillance of SARS-CoV-2 Lineages Indicates Early Circulation of P.1 (Gamma) Variant of Concern in Southern Brazil.

The SARS-CoV-2 P.1 lineage emerged in Amazonas (AM), North Brazil and its evolution has been dynamically reported associated with increased transmissibility and/or immune evasion. Here, we evaluated the lineages circulating in 29 cities in Rio Grande do Sul (RS), Southern Brazil between March 2020 and May 2021 and investigated the genetic events associated with the emergence of the P.1. A total of 202 oro/nasopharyngeal SARS-CoV-2 specimens from patients during routine hospital care were submitted to whole-genome sequencing. Phylogenetic and Bayesian Evolutionary Analyses of the P.1 lineage were carried out to determine the relationship between sequences from RS and AM and dated their common ancestor and origin. One hundred six (53%) sequences were assigned as P.1 and most carried the 22 lineage-defining mutations. All the P.1 sequences included other important mutations, such as P314L and R203K/G204R, and revealed a high genetic diversity in the phylogenetic tree. The time-scaled inference suggests that the oldest P.1 sequences from different Brazilian states share a ancestor with those from AM, but the origin of some sequences from RS is unknown. Further, the common ancestor of sequences from RS is dated to mid-June/July 2020, earlier than those previously reported from AM. Our results demonstrate that there is a high degree of genetic diversity among P.1 sequences, which suggests a continuous evolution and community spread of the virus. Although the first P.1 outbreak was reported in AM, the lineage was associated with multiple introductory events and had already been circulating in Southern Brazil prior to November 2020.